Carboxylic acids and/or esters are major components in biomass and/or bio-oils. Bio-oils typically contain a signification quantity (up to 30 wt %) of carboxylic acids, which provides these liquids with high acidity and corrosiveness. The high reactivity of acids leads to instability of the bio-oil. These undesired properties, along with the high amount of hydrogen consumed by carboxylic acids during hydrodeoxygenation to hydrocarbons, make it necessary to develop techniques for effective removal of acids from bio-oils. The conversion of carboxylic acids and/or esters to compounds with low oxygen content, such as ketones, is an important chemical process that adds commercial value to biomass and/or bio-oil. One reaction for this conversion, ketonization, which converts carboxylic acids or esters into ketones by decarboxylation, is useful for the production of symmetric and non-symmetric ketones. Catalytic ketonization in an important method for ketone production and upgrading of fuels, including but not limited to bio-oils, by increasing the heating value and stability. The utilization of biomass to produce fuels comprising the conversion of carboxylic acids and/or esters into ketones is a promising way to sustainably produce clean energy and alleviate our societal and economic dependence on fossil fuels.
Catalytic ketonization by metal oxides has been reported. The known methods require high temperature and/or high pressure which lead to many problems, including but not limited to undersirable phase transformations of the catalysts and increased reactor pressure drop. When the feed composition comprises components other than carboxylic acids (or esters) to be converted, unwanted reactions can happen to the other components, which need to be minimized or avoided especially in the upgrading of bio-oils.